Detection of Genotype 4 Swine Hepatitis E Virus in Systemic Tissues in Cross-Species Infected Rabbits

Abstract

Increasing evidence demonstrates that hepatitis E virus (HEV) can be transmitted across species. According to previous reports, swine HEV has two genotypes, genotype 3 and 4, and both can infect humans by the fecal-oral route. Thus, it is crucial for the control of HEV zoonotic transmission to evaluate the dynamics of viral shedding and distribution in different tissues during cross-species infection by HEV. In this study, rabbits were infected with genotype 4 swine HEV by the intraperitoneal route. The results showed that HEV RNA not only shed in the feces but also in the saliva of some rabbits during infection with swine HEV. Viremia appeared late after infection, and anti-HEV IgG was not obvious until the appearance of high viremia levels. After the rabbits were euthanized, a histopathological examination showed that the livers developed overt hepatitis accompanied by an elevation of alanine aminotransferase (ALT) and aspartate transaminase (AST). Furthermore, HEV RNA was detected in various tissues, especially in the salivary glands and tonsils. Subsequently, negative-stranded HEV RNA was practiced in tissues with positive HEV RNA, which demonstrated that HEV replicated in the tissues. Next, we harvested additional tissues from the liver, salivary gland, tonsil, spleen, thymus gland, lymph node and intestine, which are known as replication sites of swine HEV. Additionally, we also observed the HEV antigen distributed in the organs above through immunohistochemical staining. These results demonstrate that rabbits could be used as an animal model for researching cross-species infection of genotype 4 HEV. It is also noteworthy that HEV can shed in the saliva and presents the risk of droplet transmission. These new data provide valuable information for understanding cross-species infection by HEV.

Cross-Species Transmission of Swine Hepatitis E Virus Genotype 3 to Rabbits

“…Rabbits inoculated with human HEV-3 showed poor infectivity with only seroconversion, but not viral shedding [23]. Other studies demonstrated that rabbits infected with human and swine HEV-4 strains could induce viral shedding and seroconversion, similar to the results presented here [23,24,34].…”

“…Their ALT and AST levels remained in the normal ranges. However, elevation of ALT was observed in rabbits infected with both human and swine HEV-4 strains [23,24,34]. These discrepancies could be attributed to differences in the virulence and dose of viruses used in the different studies.…”

“…However, more convenient animal models for the study of HEV cross-species transmission are required. Rabbits can be infected with wild boar HEV-3 and swine HEV-4 [34][35][36]. However, some argue that cross-species transmission of swine HEV-4 and rabbit HEV does not happen between rabbits and pigs that are reared in animal farms in the same regions [37][38][39].…”

Detection of hepatitis E virus RNA in saliva for diagnosis of acute infection

“…Several in vivo models including rabbit and swine have isolated HEV genotype 4 that was shed in saliva in the salivary glands and tonsils (Williams et al., ; Wu et al., ). Furthermore, negative‐stranded HEV RNA has also been detected in the salivary glands, suggesting that there may be extrahepatic sites of replication (Williams et al., ).…”

Synthetic Peptides Containing Three Neutralizing Epitopes of Genotype 4 Swine Hepatitis E Virus ORF2 induced Protection against Swine HEV Infection in Rabbit

“…Previous reports had demonstrated rabbits to be susceptible to experimental infection by genotype 4 human and pig HEV isolates [23][24][25], prompting the use of rabbits as an animal model for studying HEV pathogenicity. Importantly, a rabbit model has many advantages [23,26], including lower cost and easier manipulation as compared with large animal models.…”